Cisco 300-540 Exam With Confidence Using Practice Dumps

In a VXLAN BGP EVPNMulti-Siteenvironment:

DCI trackingmonitors the health of the DCI links. If all DCI-tracking interfaces go down, the leaf can incorrectly keep advertising or learning remote MAC/IP reachability, leading to packet loss and sub-optimal forwarding for servers in that VLAN/L2VNI.

For proper operation, eachDCI-facing interfacemust be enabled with evpn multisite dci-tracking so that the Multi-Site border leaf tracks reachability over that link.

When using EVPN Multi-Site, BUM (broadcast, unknown unicast, multicast) traffic toward remote sites is typically handled viaingress replication, not multicast groups, for each L2VNI participating in Multi-Site. The configuration snippet shows an L2VNI (vn-segment 16535) still mapped to mcast-group 239.1.1.0, which is inconsistent with Multi-Site recommendations and contributes to packet loss.

Therefore, to fix the problem:

Enable DCI tracking on the uplink:

interface Ethernet1/1

evpn multisite dci-tracking

This restores proper DCI-link state monitoring for Multi-Site. →Option C

Change the L2VNI behavior from multicast to Multi-Site ingress replication:

Under the VNI for VLAN 11, configure:

evpn

vni 16535 l2

multisite ingress-replication

or the equivalent command for the specific NX-OS release, thereby aligning the L2VNI with EVPN Multi-Site design and eliminating packet loss. →Option D

Options A and B are ELAM (embedded logic analyzer) filters used only for packet capture and do not resolve the forwarding issue.

Option E is an ACL line unrelated to EVPN VXLAN or DCI tracking and does not address the underlying problem.

Comprehensive and Detailed Explanation

BGP Flowspec allows routers to distributetraffic-filtering rulesusing BGP NLRI.

To enable Flowspec, after neighbors are configured, the essential next step is:

✔Activate the Flowspec address-family under BGP

Example:

router bgp 65000

address-family ipv4 flowspec

neighbor X.X.X.X activate

exit-address-family

This enables:

FlowSpec NLRI exchange

Distribution of drop rules (rate-limit, redirect, null route, etc.)

Automatic ACL/class-map/policy-map generation on edge routers

Why the other options are incorrect:

B. Set BGP routing process→ already done when neighbors were configured

C. Activate neighbors→ only makes senseinsidean address-family; flowspec AF must be enabled first

D. Configure route reflector→ optional and not required for Flowspec to operate

Thus, the correct next step isA. Configure Flowspec for the BGP address-family.

Comprehensive and Detailed Explanation (Cisco NFVI / Virtualization Knowledge)

SR-IOV (Single Root I/O Virtualization)allows a VM to access the network interface hardwaredirectly, without going through the hypervisor’s virtual switch.

This is achieved by:

Assigning Virtual Functions (VFs) directly to VMs

Allowing high-performance, low-latency packet I/O

Bypassing the hypervisor datapath

Therefore, SR-IOV doesnotbypass the guest OS; it bypasses thehypervisor I/O virtualization layer, delivering near-native performance.

Thus the correct answer isC.